Sintered and paste positive nickel electrodes for use in an alkaline storage battery, such as a nickel-hydrogen battery, a nickel-cadmium battery and the like, are known. The paste electrodes in particular have drawn attention since it is possible to provide a high-capacity battery using paste electrodes.
However, as compared with sintered nickel electrode plates, paste nickel electrode plates are less advantageous with respect to their coefficient of utilization and rapid discharge characteristics. To increase the conductivity and coefficient of utilization while minimizing the polarization of the paste electrodes, a paste nickel electrode plate has been proposed wherein during manufacture a nickel (Ni) powder is added to a cobalt oxide (CoO) powder or the like to form an electroconductive material which is mixed with an aqueous thickener solution. This mixture is kneaded together to form a paste. A porous metal base plate or substrate is filled with the paste and the pasted substrate then dried and roll-pressed.
It has been found that when a CoO powder is used as an electroconductive material, the coefficient of utilization of the electrode is lowered due to the formation of Co.sub.3 O.sub.4 on the surfaces of the particles of the CoO powder. Thus, CoO powder conventionally is manufactured in a process wherein a Co compound, such as cobalt hydroxide, is burned or baked in a nitrogen gas atmosphere to form CoO. The resultant CoO powder is then cooled with nitrogen gas. However, if the CoO powder is left in the ambient atmosphere for a long period of time or if a paste electrode plate containing the CoO powder is exposed to the ambient atmosphere for a long period of time, the surfaces of the CoO powder are oxidized and Co.sub.3 O.sub.4 is formed thereon. Accordingly, when CoO powder manufactured by conventional methods is used as an electroconductive material in a paste nickel electrode, a lower coefficient of utilization results.